Fiji's political parties are racing to meet tonight's midnight deadline to re-register as political entities.

Under strict new rules imposed by the coup-installed government, parties need to prove they have 5,000 members, an English name and are not led by anyone who is also a trade union leader.

They must reapply before midnight, then wait three weeks to discover if the Registrar of Political Parties approves of their application.

Fiji's oldest party, the National Federation Party, has been the first to reapply, after managing to gather 8,000 members.

Only parties which have successfully reapplied will be allowed to contest the 2014 election.

Analysts say they are concerned that political debate will be stifled in Fiji over the next month, as parties wait to discover if their re-registration has been approved.

Major parties have launched a legal challenge to the decree enforcing the tough new rules.

One of the lawyers launching the challenge, Rajendra Chaudhry - son of the Fijian Labour leader - says things won't go well for the government if they try to strip parties of their assets.

"I don't think these political parties and the people that support them would sit idly and see a corrupt regime, and unaccountable regime, an unelected and most importantly an illegal regime, seize assets which belong to the people," Mr Chaudhry told Radio Australia's Pacific Beat.